2611 rename fetch data (#2689)

* Replace fetch data with preload terminology
- Deprecate `-fetchData` and `-clearFetchedData` in favor of `-preload` and `-clearPreloadedData`
- Move `-setNeedsPreload`, `-recursivelyPreload` and `-recursivelyClearPreloadedData` to ASDisplayNode+FrameworkPrivate.h
- Update internal implementation, comments and tests

* Folllow up on #2642:
- Remove -preload and -clearPreloadedData in favor of -didEnterPreloadState and -didExitPreloadState.
- -didEnterPreloadState and -didExitPreloadState call the deprecated -fetchData and -clearFetchedData methods if they are overriden.

* Missed one in a test

* Get rid of behavior change for now.

* Revert more behavior changes, fix tests.

* Don't need these anymore.

AsyncDisplayKit/ASCollectionNode.mm

@@ -167,10 +167,10 @@
   [self.rangeController clearContents];
 }
 
-- (void)clearFetchedData
+- (void)didExitPreloadState
 {
-  [super clearFetchedData];
-  [self.rangeController clearFetchedData];
+  [super didExitPreloadState];
+  [self.rangeController clearPreloadedData];
 }
 
 - (void)interfaceStateDidChange:(ASInterfaceState)newState fromState:(ASInterfaceState)oldState